1. Field of the Invention
This invention relates to an electronic component mounting apparatus, and more particularly to an apparatus for efficiently mounting various kinds of electronic components such as chip-type components on a substrate at a high speed and with high accuracy.
2. Description of the Prior Art
A typical electronic component (hereinafter also referred to as "chip") mounting apparatus of such type which has been conventionally proposed and used for mounting chips on a substrate is generally constructed in such a manner as disclosed in, for example, Japanese Patent Application Laying-Open Publication No. 265223/1986. More particularly, the conventional chip mounting apparatus is so constructed that electronic components or chips are picked up one by one in succession from a chip feed section using suitable means, transferred to an intermediate station through suitable means and then taken out or extracted one by one in order by means of a chip mounting head. The extracted chip is then deposited or placed at a predetermined position on a work by the head.
In the conventional chip mounting apparatus, the intermediate station and mounting head each are adapted to handle only one chip in each chip mounting operation, so that when an increase in the number of chips to be handled causes reciprocating movement of the chip mounting head to be increased correspondingly, resulting in working efficiency in the chip mounting operation being deteriorated. Thus, it will be noted that the conventional chip mounting apparatus fails to simultaneously treat a plurality of chips in each chip mounting operation.
Another conventional device of such type is disclosed in U.S. Pat. No. 4,644,642 issued to Hendrik on Feb. 24, 1987. In the device disclosed, a number of components are simultaneously picked up in presentation positions by a pick-up device having a number of pick-up elements. Then, the pick-up device is moved to a position over a substrate and each of the pick-up elements in succession is moved to a position over the desired position on the substrate by movement of the pick-up device and/or the substrate with respect to one another. Thereafter, the relevant component is deposited and released in the relevant position by the pick-up element.
Thus, in the device of the U.S. Patent, the single pick-up device is reciprocated directly between the presentation positions and the substrate, so that much time is required for transferring the chips from the presentation positions to the substrate. Also, in the device, any consideration is not given to a time reduction in deposition of the components on the substrate which amounts to a large part of all time required in a component mounting operation. Therefore, the conventional device fails to efficiently practice the mounting operation at a high speed. Further, the device disclosed is not adapted to carry out positional correction of the picked-up component before deposition of the component on the substrate, accordingly, it cannot carry out accurate positioning of the chip with respect to the substrate.
A further conventional electronic component or chip mounting apparatus is proposed which includes a mechanism for positioning a chip, as suggested in Japanese Patent Application Laying-Open Publication Nos. 264788/1986, 214692/1987 and 229900/1987 by the assignee. The chip positioning mechanism disclosed in each of the Japanese publications is adapted to carry out positioning of a chip while nipping the chip through four side surfaces of the chip. Therefore, the mechanism fails to cause a single positioning member to concurrently position a plurality of chips.
In view of the foregoing, the assignee proposed a chip positioning mechanism constructed so as to position a chip based on its two surfaces, which is disclosed in Japanese Patent Application Laying-Open Publication No. 32692/1987. In the proposed mechanism, a support on which chips are supported is moved obliquely with respect to a positioning member so as to have components of movement in both X and Y directions. Unfortunately, the mechanism is for the purpose of accurately positioning only one chip in each chip mounting operation, accordingly, it cannot concurrently position a plurality of chips in each chip mounting operation.
A chip mounting head of the index rotation type has been used as a chip mounting head for the conventional chip mounting apparatus, which is disclosed in Japanese Patent Application Laying-Open Publication No. 30399/1987. The head includes a plurality of suction pins arranged at equal angular intervals on an index head and is adapted to cause each of the suction pins to be rotated by a predetermined angle when the index head is moved to a particular position.
Another chip mounting head is also proposed which has a plurality of suction pins arranged thereon in a row and is mounted on a lower side of an X-Y table. In the chip mounting head, the suction pins on which chips are respectively held are simultaneously moved to a position above a printed board or substrate to deposit the chips on the printed board in sequence. In this instance, when rotation angles of the suction pins are set in sequence independent from one another as in the mounting head of the index rotation type described above, a lot of time is required to set a posture of a chip held on each of the suction pins at a predetermined angle.
The words "electronic component mounting operation" or "chip mounting operation" used herein generally indicates an operation ranging from extraction of chips from a chip feed section to deposition of the chips on a substrate.